Elevated Maintenance
Costs in an Anuran (Rana catesbeiana)
Exposed to a Mixture of Trace Elements during the Embryonic and
Early Larval Periods

Christopher L. Rowe
Owen M. Kinney
Roy D. Nagle
Justin D. Congdon

University of Georgia,
Savannah River Ecology Laboratory, Aiken, South Carolina 29802

ABSTRACT

We investigated the relationship between
maintenance costs (standard metabolic rates, measured as 0,
consumption at rest) in tadpoles of the bullfrog, Rana
catesbeiana, and exposure to contaminants in a coal
ash-polluted habitat (characterized by a variety of trace
elements). We compared metabolic rates of tadpoles collected from
the polluted site with those from an unpolluted reference pond.
Tadpoles collected in the polluted site had 40%-97% higher
standard metabolic rates than those collected from the reference
pond. We also reciprocally transplanted eggs of the bullfrog
between the polluted site and another reference pond and compared
standard metabolic rates of tadpoles at 25 and 80 d posthatching.
Metabolic rates of tadpoles raised in the polluted site were from
39% to 175% higher than those raised in a reference pond,
depending on tadpole age and temperature at which metabolic rates
were measured. There were no effects of site of origin of the
eggs (polluted or unpolluted) on metabolic rates. Survival to
hatching did not differ between sites, although survival to the
end of the experiment (80 d posthatching) was lower in the
polluted area than in the reference site. Surviving tadpoles were
larger in wet body mass in the polluted site than in the
reference pond, possibly due to lower survival in the former, but
there was no relationship between survival and metabolic rate. It
is clear that some feature of the polluted habitat was
responsible for causing substantial elevation of standard
metabolic rates of tadpoles. We hypothesize that the mixture of
trace elements present in sediment and water in the polluted site
was responsible for the observed physiological differences.